Start by loading the NHANES data and dplyr package.

library(dplyr)
library(NHANES)
data(NHANES)

Exercise

1. Compute a summary with the mean and standard deviation of the BPSysAve variable for females, but this time for each age group separately rather than one selected decade. The age groups are defined by AgeDecade variable. Store the result in a data frame summary_female with a mean and a sd variable.

   Hint

   Rather than filtering by AgeDecade and Gender, filter by Gender and then group by AgeDecade before summarizing.

2. Repeat exercise 1 for males. Store the result in summary_male.

3. We can actually combine both summaries for exercises 1 and 2 into one summary. This is because group_by permits us to group by multiple variables (group_by(dataframe, var1, var2, .., varn)). Obtain one big summary with the blood pressure mean (mean) and standard deviation (sd) per age category (AgeDecade) per gender (Gender). Make sure the order of the variables in the group_by function is correct. Store the result in a data frame summary_complete.